The purpose of this inter-agency agreement is to provide funds to the VA Puget Sound Health Care System (VAPSHCS) to support the Long-term Oxygen Treatment Trial (LOTT) contract program. Severe COPD is often fatal, but long-term treatment with supplemental oxygen improves survival in patients with COPD and severe resting hypoxemia. However, it is not known if long-term oxygen prolongs life in those with less-than-severe hypoxemia.